Apparatus for producing pseudostereophonic effects



Aug. 7, 1962 J. M. HANERT APPARATUS FOR PRODUCING PSEUDO-STEREOPHONICEFFECTS Filed April 2'7, 1960 OAMPUFIER? o r .i. I2 /-24 T DKIVEEAMPUFIEK IN VEN TOR.

BY gm M J'a/nmii United States Patent 3,043,072 APPARATUS FOR PRODUCINGPSEUDG- STEREOPHONIC EFFECTS John M. Hanert, Des Plaines, 11]., assignorto Hammond Organ Company, Chicago, Ill., a corporation of Delaware FiledApr. 27, 1960, Ser. No. 24,944 4 (Ilairns. (Cl. 84-l.24)

The invention relates generally to apparatus for introducingpseudo-stereophonic effects in music derived from a single source ofelectrical signal which does not have any or a suflicient amount ofreverberation.

It is an object of the invention to provide a simple apparatus which maybe made at relatively low cost and will modify music in the form ofelectrical signals derived from any source such as radio receiver,photograph, microphone, etc., by changing a portion of the signals fromthe source into reverberative signals and supplying some of theunmodified signal from the source and some of the reverberated signalsto a pair of electroacoustic transducers such as speakers or earphones.

A further object is to accomplish the foregoing result by using a pairof mechanical reverberation devices coupled to a single driver and twoseparate output pickups.

Other objects will appear from the following description reference beingmade to the accompanying drawing.

It is now well recognized that the enjoyment of music may be greatlyenhanced if it is heard in a reverberative enclosure or if thereverberation effect is added to the music and that this advantage isgreatly enhanced if the reverberation effect supplied to the soundreaching one of the listeners ears differs in character from thereverberation applied to the music heard primarily by the other ear.However, the cost of reverberation apparatus in the past has been ratherhigh, but by the use of the present invention, a number of the parts ofone of the two reverberation devices are eliminated, with consequentsubstantial reduction in cost.

The single FIGURE of the drawings is a diagrammatic representation ofmechanical elements and electrical circuitry constituting the invention.

In the drawing, a source 10 of musical tone signals which, as previouslyindicated, may be from any phonograph, radio receiver, or the like, issupplied to the input of anamplifier 12, the output of which is coupledthrough resistors R14 (which are preferably variable) to switches 16 and18 which may selectively supply the signals either to speakers 20 and 21or to earphones 22. and 23 respectively.

In addition, the output of the amplifier 12 is supplied to a driver(electromechanical transducer) illustrated as an electromagnet 24 havingan armature 26 associated therewith. The driver armature 26 ismechanically connected to a (mechanico-electric transducer) pickuparmature 28 through a coil spring 30 and it is similarly connected to apickup armature 32 through a coil spring 34.

The armatures 28 and 32. have electromagnetic pickup coils 36 and 37associated in a manner as to have the inductance changed by thevibrations of the pickup armatures Z8 and 32. Y

The outputs of the pickups 36 and 37 are respectively coupled toamplifiers 38 and'39. The output of the .am-

plifier 38 is connected through a variable resistor R40 to the switch 16and the output of the amplifier 39 is Patented Aug. 7, 1962 in thecompressional or torsional mode, and the coil springs are preferablywound in such manner that the signals are transmitted solely ascompressional vibrations or solely as torsional vibrations. The driversand pickups may be of any conventional construction, for example, thepickups may be similar to those used in the pickup heads of phonographs.

Because the portion of the sound reaching one ear is in various phaserelations and frequency response, as compared to that reaching the otherear, the listener will perceive the music as he is accustomed to hearingit in an auditorium having good reverberation effects due to itsparticular size and construction. The frequency spectrum of the music asheard will not appear to contain nulls or peaks because tworeverberative signals heard will never be in the same or opposite phaseat any frequency, because even though the coil springs are apparentlyidentical, in dimensions and the metal of which they are made, therewill inevitably be some variations, even though minute, but sufficientto prevent the reverberated signals of any particular frequency fromarriving at the two cars in phase for any perceptible time interval. Thephase relationship of the signals will be as random as they are heard inan excellent auditorium, and thus to the listener the music will besensed as if the listener were hearing the sound as reflected fromnumberless surfaces in the usual random manner.

While I have shown and described a particular embodiment of myinvention, it will be apparent to those skilled in the art that numerousmodifications and variations may be made in the form and constructionthereof, without departing from the more fundamental principles of theinvention. I therefore'desire by the following claims to include withinthe scope of my invention all such similar and modified forms of theapparatus disclosed, by which substantially the results of the inventionmay be obtained by substantially the same or equivalent means.

I claim:

1. In an apparatus for improving the music as heard by the listener inwhich the source is a single audio frequency electrical signal, anelectroacoustic driver having input terminals connected to the source,the driver having a movable element which moves in response to saidaudio frequency signal, a pair of solid delay introducing soundtransmission springs having input and output ends, means connecting theinput ends of said devices to the movable element of the driver, a pairof mechanico-electric pickup devices having movable parts connectedseparately, one to each of the other ends of said springs, a pair ofelectroacoustic translating means and means coupling the pickupdevicesseparately, one to each of the electroacoustic translating means.

2. The combination set forth in claim 1 in which means are included forcoupling the signal from the source without delay to each of theelectroacoustic translating means. 3. The combination set forth in claim2 in which at least one of the coupling means includes a variableresistor for controlling the intensity of the sound produced by theelectroacoustic translating means.

4. The combination set forth in claim 1 in which the means connectingthe sound delay transmission devices to the movable element of thedriver and to the movable parts of the pickupsconstitute means forreflecting sound vibrations.

References Cited in the file of this patent UNITED STATES PATENTS

